Phonograph pickup device



PHONOGRAP'H PICK-UP DEVICE Ffled May 5, 1945 3 Sheets-Sheet l JNVENTOR.

RALPH M. HE/NTZ y 'ATTORNE Y Jan. 7,1947. l?. M. IHEINTZ 2,413,971

'PHONOGRAPII PICK-UP DEVICE FiledMay 5, 1945 3 Sheets-Sheet 2 INVENTOR.

I RALPH M. Hmrz ATTORNEY Jan. 7, 1947. R. M; HE| NTZ 2,413,971,

PH ONOGRAPH PICK-UP DEVICE Filed May 5, 1945 s sheets-sheet a I h INVENTOR. RALPH M HEINTZ ATTORNEY Patented Jan. 7, 1947 mesne assignments, to Jack & Heintz Precision Industries, Inc., Cleveland, Ohio, a corporation of Delaware.

Application May 5, 1945, Serial No. 592,183

The present invention relates in general to electromagnetic transducer devices, orpickup units, for converting mechanical motion into electrical voltages and more particularly to improvements in such devices as; appliedito phonugraph and vibration pickups and the like.

One of the primary objects oi'the invention is to provide an improved moving conductor and method of making and assembling the samein a workingpickup unit to, provide a simple, inexpensive and eflicient pickup unit Whose voltage generating element is of simplified construction of minimum weight andwhose resilient mechanical suspension is inherently free to move transversely and rigid against vertical movement and whose conductor generating element develops voltages only in response to such transverse mo- ,tion of the suspension. l I

The present invention, as applied for example to a phonograph pickup unit, utilizes the well known principle of generatingelectrical voltages by moving a conductor in a magnetic field at right angles to the direction of j flux by whlch the voltages will be proportional to the velocity of mechanical movement. v

Briefly the invention contemplates the stamping and subsequent bending of a single continuous piece of sheet metal so as to form its own spring suspension and the mounting of it on a frame through a continuous magnetic iron core in such a manner as to form a single turn around the transformer core. The transformer core also has wound around it a coil having many times the impedance of the single turn voltage generating loop. A permanent magnet is mounted in i such a manner as to provide the magnetic flux through which the conductor moves. l

With the foregoing and other objects in View the invention resides in the combinationfof parts set forth in the following specification and appended claims, certain embodiments thereof being illustrated in the accompanying drawings, in which:

Figure 1 is a view in perspective of one form of phonograph pickup unit employing two conductors for voltage generation; I V

Figure 2 is a view in plan of the punched out sheet metal blank before bending to form a pickup loop;

Figure 3 is a view in perspective oi the"blank after being bent to form thepickup loop;-

Figure 4is a fragmentary. view in perspective view of another type of pickup loop showing the same and the needle partly broken away; a

Figure 5 is a plan viewof thestarnped out blank G'Claims. (01. 179-10041) 2 priorto bending. to formthe pickup loop of Figure 4;

Figure, 6 is a view, in-elevation of theneeclle, or stylus, and its holder in vertical section; Figure 7 is a plan view of another modified form of stamping prior to bending to form a pickup loop; j i

4;: Figure 8 is a view in perspective of the stamping of Figure 7 bent to form-a pickup loop; and

Figure 9 is a view in perspective of another form of phonographpickup unitemploying a single conductor for voltage generation and a loop of the type of Figure 8. Referring more particularly to the drawings, Figures 1, 2 and 3 show successive stages in-the formation of oneform of phonograph pickup uni-t. Figure 2 shows a one piece stamping of sheet metal having preferably the proper electrical conductivity and mechanical strength. Such a metal may be one of the various aluminum alloys such as 17S, 24S, 75S or one of the berylliurn 'aluminurn s. It may also be one of the beryllium copper alloys or copper-nickel-manganese alloys. Thefthickness of the sheet may rangefrom as low as from .002 to .008 inch. depending upon the specific gravity, the electrical conductivity and elastic properties of the alloy. The form of pickup unit shown in Figure 1 includes a supportingframe] of non-conducting material. for supporting a two pole permanent magnet 2 and a vertically'spaced soft iron magnetic backing plate 3 therefor. It also supports a magnetic cored and a coil 5. The. pickup, generally indicated at 6, is formed by stamping out a single piece flatstamping of sheet metal as shown in Figure 2." This single piece includes two longitudinally extending legs land 8 of unequal length, a cross band 9, a recess I0 and an angular cross band including transverse arms II and, longitudinal arms 13 and I4 and cross arm I 5. The sheet 6 is then physically bent into the form shown in Figure 3 in which the two legs "I and 8 andthe cross band l5 become vertical elements as well as the end portions I and 8' of legs I and8 which are bent inwardly in spaced overlapping relationship. The pickupinits form of Figure 3'is the secured to the frame byscrews l6 passing through legs 1 and 8 and ,the frame 6 in such a manner that. the core 4 passesaround the cross 'band 9 and through appropriate cut-outv recesses in the frame so that the coil is positioned longitudinally of the frame. The core is mechanically just short of-being a continuous circle but is substantially continuous magnetically, The-permanent magnet 2 rests on the frame and is longitudinally spaced from the coil. The two pole pieces I! and I8 of the permanent magnet extend longitudinally of the frame and their bottom surfaces are elevated with respect to the base of the permanent magnet and extend over the legs 13 and Id of the pick-up loop in spaced relationship. Beneath legs [3 and I4 is mounted a magnetic backing plate 3 which has pole pieces l9 and 20. The means of attachment of the permanent magnet and the magnetictbacking plate to the frame may comprise screw bolts 2| and washers '22, or the like. Thebentportions 1' and 8' of legs I and 8 form'a'support for-a stylus collet, or block, 23 which receives a stylus, or needle, 24 which may be held in position in the collet by the conventionalhand knob '25 for operating a set screw for this purpose.

In this arrangementihe pick-up loopby attachment to the frame-constitutes its own resilient'mechanicalsuspension that is free to move transversely and to a very limited degree about its own'longitudlnal axis but rigid to resist vertical -movement due to the verticality of legs I and- 8. The positioning of legs I 3 and M between the pole pieces 11 and I9 and'between I3 and 25 constitute legs 13 and M as conductors in-which the voltages are generated. The permanent magnet develops poles in its pieces l! and IGbGIOW which the pieces l9 and 20 of the magneticbacking plate 3 serves to complete the magnetic circuit. Since pole ll has a magnetic polarity opposite to that of pole I8 the voltages generated in legs l3-and l4 of'the pick-up loop wil1=be oppositelydirected and will therefore be additive since't-hese voltages aregenerated in a continuous loop which links themagnetic core 4. A voltagewill be generated in coil 5 since it serves-as a secondaryof a'transformer having a single turn primary. theflloop 6 of Figure 3 ;when installed in the assembly of Figure ,1 servesnot only as a continuous electricalloop but alsoprovides a resilient suspensiomfor the stylus 24 that permits transverse movement thereof since the verticallegs 1 and '8 of the pickup loop is transverselyflexible. It will be appreciated that it is the desireto limit thegenra ionq vol es t tran ersem m nts f the stylus and the suspension to the exclusion of ve ti movement and- .the m nimization o rotati n mov ent of th uspensio ab ut i ow lon i ud n i .LAn. alternate form .of p ununit and ,nickup loopis shown in Figures 7,8 and 9 wherein only a single conductorelement and a single ma netic sa s d- The stamp shown in Fi ur '7 and in bentform in Figure 8includescross pieces MA and. I2 and a single .1eg.,26, as distinguished from the two legs I3 and J4 of Figures 1, 2 and 3. This leg 26 is positioned between thesingle pole 21 of the permanent magnet 2A and the single pole 29 of asoft ironmagnetic hacking plate 28 and thus constitutes a single conductor element between the single magnetic gap. This arrangement has some inherent advantages over that shown in Figures 1,12 and 3 inthatthe current generating elementZfi is virtually coincident with the rotational aXis of 'thersuspensionmake ing the dimensional clearances 1 less critical in manufacture and assembly and reducing of undesired voltages in resp0nse to rotation and any voltages other-than those in "response to transverse -movements.

Figures 4, and 6-a-re devotedto.a modified form of-pickup loop -whichis-so formed in a single piece by stamping, or punching, and subsequent bending to support in a different manner the insulated stylus, rather than employing the conventional stylus collet of Figures 1 and 9. Here the single piece blank 63 has cross pieces MB and MB to support a leg 26A, which is comparable-to leg 26 of Figure 9 and for the same purpose. In addition the blank 6B has a tab 30. This blank is then bent into the form shown 'in Figure 4 in which the legs 1 and 8 are vertical, the extension 1 is bent downwardly and transversely inwardly and tab 30 is vertical. In addition the extension I is rolled at 3| and tab 3% is rolled at'3'2 to form a means of holding and support directly of an insulating cylinder 53 interiorly threaded to receive the screw threads 3 1 of astylus'35 having a stylus point 36.

I claim:

1. In an electromagnetic pickup unit for converting mechanical motions into electrical voltages and including a stylus, a permanent magnet and a spaced soft iron magnetic backing plate therefor. and a'substantially continuous magnetic transformer core and coil therefor and an insulated supporting frame therefor, a single unitaryelement formed'by a flat piece of stamped out sheet metal bent to include vertical suspension portions and horizontal portions therebetween, one of said horizontal portions extending through said core and another extending between said permanent magnet and its backing plate, said element being carried by said frame for supporting said stylus and for comprising a single turn around said transformer and for comprising a conductor for voltages generated by its movement between said permanent magnet and its magnetic backing plate.

2. In an electromagnetic pickup unit for converting mechanical motions into electrical voltages and including a stylus, a permanent magnet and a spaced soft iron magnetic backing plate therefor and a substantially continuous magnetic transformer core and coil therefor and a supporting frame therefor, a single unitary element formed by a fiatpiece of stamped out sheet metal bent to include vertical suspension portions and horizontal portions therebetween, one of said horizontal portions extending through said core and another extending between said permanent magnet and its backing plate, said element being carried by said frame for supporting said stylus and for comprising a single turn around said transformer and for comprising a conductor for voltages generated by its movement'between said permanent magnet and its magnetic backing plate, said vertical portions of said element being adapted to rigidly oppose vertical movements and flexibly permit transverse movements of said stylus.

3. In an electromagnetic pickup unit for converting mechanical motions into electrical voltages and including a permanent magnet and a spaced soft iron magnetic backing plate therefor and a substantially continuous magnetic transformer core and coil therefor and a supporting frame therefor, a stylus and a single unitary metallic element carried, by said frame for supporting said stylus and having a portion so positioned with respect to said transformer as to comprise a single turn around the same and having a I portion extending between said permanent magnet and its magnetic backing plate to constitute a conductor of voltages generated by its movements therebetween.

4. In an lectromagneticpickup unit for converting mechanical motions into electrical voltages and including a permanent magnet and a spaced soft iron magnetic backing plate therefor and a substantially continuous magnetic transformer core and coil therefor and a supporting frame therefor, a stylus and a single unitary metallic element carried by said frame for supporting said stylus and having a portion so positioned with respect to said transformer as to comprise a single turn around the same and having a portion extending between said permanent magnet and its magnetic backing plate to constitue a conductor of voltages generated by its movements therebetween, said element being so formed and connected to said frame as to sup-port said stylus rigidly against movement in its plane of suspension and flexibly transversely to permit transverse movement of said stylus.

5. In an electromagnetic pickup unit for converting mechanical motions into electrical voltages and including a stylus, means for creating a magnetic flux and a substantially continuous magnetic transformer core and coil therefor and an insulated supporting frame therefor, a single unitary element formed by a fiat piece of stamped out sheet metal bent to include vertical suspension portions and horizontal portions therebetween, one of said horizontal portions extending through said core and another extending through said flux creating means, said element being carried by said frame for supporting said stylus and through said for comprising a single turn around said transformer and for comprising a conductor for voltages generated by its movement in the path of said flux, said vertical portions of said element being adapted to oppose movements of said stylus in its plane of suspension and flexibly permit transverse movements of said stylus.

6. In an electromagnetic pickup unit for converting mechanical motions into electrical voltages and including a stylus, a permanent magnet and a spaced soft iron magnetic backing plate therefor and a substantially continuous magnetic transformer core and coil therefor and an insulated supporting frame therefor, a single unitary element formed by a flat piece of stamped out sheet metal bent to include suspension portions and angularly disposed portions therebetween, one of said angularly disposed portions extending core and another extending between said permanent magnet and its backing plate, said element being carried by said frame for supporting said stylus and for comprising a single turn around said transformer and for comprising a conductor for voltages generated by its movement between said permanent magnet and its magnetic backing plate, said suspension portions of said element being adapted to rigidly oppose movements in its plane of suspension and flexibly in a plane transverse thereto to permit movements of said stylus in said transverse plane.

RALPH M. HEINTZ. 

